/Engine/Plugins/Media/MediaIOFramework/Source/MediaIOCore/Public/MediaIOCoreAudioOutput.h
Audio capture that automatically registers to the main engine device. Also, handles automatically registering to the current PIE world's audio device. This audio capture is used by default if no audio device handle is specified when media capture creates the audio output.
class FMainMediaIOAudioCapture : public [FMediaIOAudioCapture](API\Plugins\MediaIOCore\FMediaIOAudioCapture)